1. Field of the Invention
This invention relates to a process and apparatus for regulating quantities of fresh air in high-speed trains by means of pressure-wave valves.
2. Description of the Prior Art
Pressure-wave valves are typically utilized for the protection of equipment, through which a gaseous or vaporous medium, particularly air, flows, against pressure waves or increased air velocity, particularly in ventilation and/or air conditioning systems. From British Pat. No. 569,013, for example, a pressure wave protective flap is known having a frame which can be mounted in a ventilating duct and to which slats, constructed as articulated flaps with V-shaped cross section and a swivel axis at the vertex, are, independently of each other, supported rotatably, about several mutually parallel axes and which, when a given air velocity is exceeded and/or in the case of increased air pressure, are acted upon, in the direction of closing and thereby close off the duct cross section automatically until the air velocity and/or the air pressure have dropped to normal value.
A V-shaped cross section is also shown by the articulated flap-like slats according to German Utility Model (DE-GM) 7 133 893 which relates to a ventilation window for housings of exposed transformer stations. In order to avoid the escape of hot or even burning gases through the ventilating window to the outside in the case of a short circuit, the articulated flap-like slats are supported on the narrow sides thereof by means of bearing pins in bearing holes of the frame in such a manner that they are swung by the internal excess pressure into a closed position, wherein they overlap each other. To avoid vibration or chattering of the free-swingingly suspended flaps, due to external influences, for instance, vibrations or also changing air pressure, the exposed edges of these articulating flap-like slats can be restoringly spring-loaded by a yielding force, specifically springs.
In connection with high speed trains, such valves are designed to close for a specified period of time in the event of impermissibly great differences in pressure between the interior of the coach and the surroundings, thereby preventing impermissible changes in the interior pressure of the coach itself and damage to the ventilation and air conditioning systems thereof. A device responsive to close a flap in response to an impermissible increase in interior pressure is, for example, disclosed in German Published Specification DE-PS 36 18 292.
It is disadvantageous that the valves of all previously known pressure valve devices, including those described above, are only actuatable into one of two possible positions, fully open or fully closed. While such operation is consistent with the protection of equipment from pressure waves and sudden increase s in air velocity, it does not provide any means for regulating the amount of air intake while pressure differentials are at permissible levels.
Accordingly, it is an object of the present invention to provide a process by which the flow of air into a high speed movable compartment, such as a train car, may be economically regulated in accordance with such variable factors as the number of passengers on board and the temperature outside the compartment.
It is a further object of the present invention to provide an improved pressure-wave valve apparatus which is capable of performing the enhanced flow regulation which characterizes the aforementioned method.